Air filter



Jme 28, 193. A. J. J. Pol-:AMANr Er AL. ZJZZM AIR FILTER FilelNOv. 22,1954 2 Sheets-Sheet 2 .lI-lllLgllll atented June 28, 193

TER

Armand ll. l'. Poelman, Saint-Maurice, and

Robert Schneider, Paris, France Application November 22, 1934i, SerialNo. 754,314 In France December 2, 1933 5 Cla. ms.

The present invention relates to air filters intended to stop dust andliquid vesicles which cannot be stopped by chemical agents nor byadsorbing bodies.

This problem is particularly important for the protection of civilianpopulations and of military formations, in the case of a chemical war,since some noxious products such as arsines are intended .to act in theform of an extremely ne and penetrating fog. l

It has already been proposed to make use of paper lters for stoppingproducts of that kind.

The object of the present invention is to provide a paper filter havinga very large active surface and occupying a space as reduced aspossible, this filter being easy to manufacture andl ail'ordingsatisfactoryv duid-tightness at thejoints.

To this effect, according to our invention we make the filter from asheet or band of paper which is plaited, preferably parallelly to one ofits edges, the joint between the filter mounting and the edges of theplaits being obtained through a luting cement.

Preferred embodiments of our invention will be hereinafter described,with reference to the accompanying drawings, given merely by way ofexample, and in which:

Fig. 1 is an axial sectional view of an air purifying device includingin the same case a filter according to the present invention and anadsorbent system.

Fig. 8 is a section of the same filter in a direction parallel to theplaits of the paper;

Fig. 9 is an axial section of a modification;

Fig. 10 is a plan view of another modification; Fig. 11 is a sectionalView on the line jII-II of Fig. 10.

In the embodiment of Fig. 1, the case of the gas mask comprises afrusto-conical weldless portion I forming a housing for active carbon I'for instance. It is prolonged by a cylindrical threaded portion 2intended to receive the air filter. On its opposi e side it is providedwith a threaded tube-3i fixation to the mask proper. The space fo activecarbon I is limited by a perforated end plate II inserted with a force tin portion I and by a partition 5, also apertured, welded at severalpoints to the case.

A shoulder 6 provided between parts I and 2 forms a seat for a rubberpacking ring 6' against which the mounting or frame f the filter isapplied.

Said filter consists of a band of paper plaited at right angles to itslength and the ends of which have been fixed together by` gluing, so asto form an annular element of star-shaped cross section, with radialplaits, as shown at 'I in Fig. 3.

At the edges of the plaits we provide, on one side, a disk 8 with acentral aperture 8' and on the other side a solid disk 9. The filter isheld between these two disks which constitute its mounting. The outeredges of disks 8 and 9 and the edge of aperture 8' are slightly bent soas to give them the shape of shallow cups. These cups are filled with aluting cement I in which the edges of the plaits of the annular paperele. ment 1 are sealed.

The peripheral portion of annular disk 8 forms a flange 80 and rubberring 6 is adapted to lit between said flange 80 and shoulder 6. Fluidtightness is ensured by the pressure exerted on this peripheral fiange80 by a hollow cylindrical .cap I0, which is screwed in the .cylindricalportion 2 of the case of the gas mask. The top II of this cap isprovided with apertures I2 disposed in a lattice-like fashion so as topermit air to penetrate into said cap while protecting the filteragainst rain. In order to make it possible to turn these apertures inthe desired direction, whatever be their positionafter screwing of capI0, the top II thereof consists `of a disk distinct from the threadedcylindrical part of cap IIl and the edges of which are maintained in agroove I3 of said cylindrical part, the disk being able to turn withan-easy fit in said groove.

Air enters through these apertures I2, flows around the periphery of thefilter, passes through the paper of which said lter is made, dust andvesicles being thus stopped, and then, through orifice 8 this filteredair iiows into the body I of the case, where carbon adsorbs noxiousgases and vapours. The purified air finally enters the to improve theresistance of the lter, it is ady an artificial ageing by means of airladen with dust. I

The luting cement utilized for ixing the filter to its disks 8 and 9 mayconsist of any matter capable of forming a fluid-tight joint between thezig-zag edge of the plaited paper element and discs 8 and 9, providedthat said matter, sui? ciently hard in its normal state, can be causedto assume a suiiiciently soft consistency, when assembling the parts ofthe filter, for permitting of embedding therein the edges of the paperelement without deformation thereof. We may for example make use ofstabilized rubber latex, containing a self-vulcanizing agent, such, forinstance, as Vulka P (piperidyldithiocarbamate of piperidin). We mayalso make use of polymerized vinyl chloride. However experience hastaught that it is particularly advantageous to have recourse to anasphalt having its melting point close to 120 C. and becoming brittleonly below 10" C. approximately. 'I'his asphalt is poured in the fusedstate in the shallow cups formed by disks 8 and 9 and the edges of theplaited paper are immersed therein.

In the embodiment of Fig. 2, the filter, which is identical to thatabove described, rests, through the fiange 80 -of its annular disk 8,upon a rubber ring 6 bearing upon the rounded edge of case I. A cover orcap I0" bears, through its lower edge, upon flange 80 against which itis strongly applied by a threaded socket I Il adapted to turn freelywith respect to case I and screwed on the threaded cylindrical part ofsaid cover I0. As apertures I2 can be turned in the proper direction byrotating cover I0 becfore lnally fixing it, the top, or end plate, II ofthis cover I0 is ihtegral with the cylindrical portion thereof.

In.the embodiment of Fig. 5, plate 8 carries a cylindrical peripheralportion 8" the height of which is greater than that of filter 1. When ythe whole is fixed to the mask, it is this portion 8" that supports theeffort exerted by apertured c ap I0 or I IJ" In the embodiment of Fig.6, the plaited paper annular element 'I that forms the filterconcentrically surrounds the active carbon case, which is locatedbetween the disks 8 and 9 of the filter.

The outer wall 5 of the box or case containing active carbon isperforated over its whole surface. On the contrary the inner wall 5" ofthis box or case is perforated only'ovr the middle portion of itsheight, in order to avoid that, due

to a settling of the carbon in the box, air may. ow through said boxwithout being puriied by passing through said carbon. i With an outerdiameter of 105 millimetres and a height of 70 millimetres, theapparatus contains 200 cubic centimetres of active carbon. The

filtering surface of the paper is then 2,250 square centimetres. Theapparatus requires onlya suction corresponding to 1,2 mm. of water foithe passage of 900 litres of air per hour.

In annular shaped filters, the faces of the plaits of the paper band canthemselves be undulated or bent, all in the samel direction, for in`-stance as shown in Fig. 4.

When it is desired to protect shelters or dugouts, it is possible, asshown in Figs. 7 and 8, to obtain plane filters of very large usefulsurface by mounting in a frame I4v a plaited sheet of 2,13%,ill1

paper I5 between wire-ganzes I6. Parallelly to the plaits the edges ofthis sheet of paper are fixed to the corresponding elements of theframe, for instance by gluing. The edges of the plaits are, as in thepreceding cases, sealed in a luting cement l', provided in channels I4'carried by the corresponding elements of the frame.

Figs. 9 to 11 inclusive show other embodiments of masks for gaies.

According to he embodiment of Fig. 9, the chamber a that contains activecarbon b or any other physico-chemical purifying agent which is maderigid with the chamber c containing the annular filter d made of plaitedpaper.

The lower edge of this chamber c is set under the bent edge of chambera, a packing annular memberbeing interposed therebetween foruidtightness'. Against this annular member is applied the edge of thepartition f that separates chamber a from chamber c. Thisv partition isprovided with an annular shallow recess adapted to contain the lutingcement in which is xed one of the edges of paper filter d. The otheredge of this filter is also luted in an annular shallow recess providedin solid disc g.

'Ihe active carbon b is maintained between a perforated disc h theperiphery of which rests against an inner shoulder of chamber a, andanother perforated dise i subjected to the action of a spring iinterposed between disc i and partition f. 'I'he carbon present in saidchamber is thus constantly compressed so as to avoid the formation ofhollow spaces therein, which would permit air to escape the action ofthe'physicochemical purifying body. Discs `h and i are provided'withannular ribs intended to improve their rigidity.

When the device is not in use, the air inlethole is stopped by means ofa rubber plug lc fixed to an arm l. In a 'like manner, the conduit m forconnecting the ldevice to the mask proper is closed by means of a screwthreaded cap n, with a packing annular member o.

In the embodiment of Figs. 10 and 11, two annular filters d, made ofplaited paper, are luted in corresponding shallow grooves provided inthe bottom of a box-'like structure p, around holes q for the passage ofair. 'I'he other edge of lters d is luted in annular shallow grooves ofsolid discs y. Boxlike structure p is provided with a' cover 1' fixedthereto and provided with a central Cil air inlet hole s. The whole isadapted to t on the opening of a flask t which contains thephysico-chemical purifying body.-

While we have, in the above description, disclosed what we deem to bepractical and eiiicient embodiments of the present invention, it shouldbe well understood that we do not wish to be limited thereto as theremight be changes made in the arrangement, disposition and form of theparts without departing from the principle of the present invention ascomprehended within the scope of the appended claims.4

What we claim I.' In combination with a mask includinga case for thepassage o'f air, and an air permeable partition of an adsorbent materialdisposed in said case-across the V`path of travel ofsaid air', a filterincluding a band of paper plaited Iacross its width and the ends ofiwhich are glued together so as to forma 4ring-shaped plaited element,two parallel rigid discs, luting cement fixing the zig-zag edges of saidannularplaited element to said discs respectively, one of said discsbeing solid and the other being provided with at least one opening inthe circular portion thereof surrounded by said annular element, andmeans for fixing said lter to said case in such manner that the secondmentioned disc is applied in a fluid-tight manner against said case withits opening opposite said .together so as to form a ring-shaped/element,

two parallel rigid discs, luting cement xing the zig-zag edges of saidannular plaited element to said discs respectively, one of said discsbeing solid and the other beingA provided with at least one opening inthe circular portion thereof surrounded by said annular element, acasing surrounding said fllter, and means for rigidly assemblingtogether in a uid-tight manner the ends of said case and said casing andthe outer periphery of the second mentioned disc in such manner that theopening thereof is located adjacent said partition.

3. In combination with a mask including an annular case for the passageof air, and an air permeable partition of an adsorbent material disposedin said case across the path of travel of said air, a filter including aband of paper plaited across its width and the ends of which are gluedtogether so as to form a ring-shaped element, two

parallel rigid discs, luting cement fixing the zigzag edges of saidannular plaited element to said discs respectively, one of said discsbeing solid and the other being provided with at least one opening inthe circular portion thereof surrounded by said annular element, anannular casing surrounding said lter having one edge rigidly xed to thecorresponding edge of said case and to the outer periphery of the secondmentioned disc in such manner that the opening of said second mentioneddisc is located adjacent said partition, and a packing member'interposed between said periphery of the second mentioned disc and theedge of atleast one of said case and casing elements.

4. In combination with a purifying device having an inlet and an outlet,and a partition of an adsorbent material interposed between said inlet.

and said outlet, a filter including a band of paper plaited across itswidth and the ends of which are glued together so as to form aring-shaped plaited element, two parallel rigid discs, luting -cementxing the zig-zag edges of said annular plaited element to` said discsrespectively, one. of said discs being solid andthe other being providedwith at least one opening in the central portion thereof surrounded bysaid ring-shaped element, and means for fixing in a uid-tight mannersaid second mentioned disc upon the inlet of said purifying device.

5. In combination with a purifying device including a cylindrical casewith an inlet and an outlet and a partition of an adsorbent materialinterposed between said inlet and said outlet, a lter including a bandof paper plaited across its width and the ends of which are gluedtogether so as to form a ring-shaped plaited element, two parallel rigiddiscs, luting cement fixing the zigzag edges of said annular plaitedelement to said discs respectively, one of said vdiscs being solid andthe other being provided with at least one opening in the centralportion thereof surround-- ed by said ring-shaped element, and means forxing in a fluid-tight manner said second mentioned disc upon the inletend of said cylindrical CaSe.

- ARMAND J. J. POELMIAN.

ROBERT SCHNEIDER.

